Final answer:
The Lady of Shalott looks out the window to experience the real world, especially after being captivated by the sight of Sir Lancelot, leading her to defy the curse and choose the reality over her limited existence.
Step-by-step explanation:
The Lady of Shalott looks out the window driven by a powerful longing to engage directly with the real world and to experience life beyond the reflections she has been limited to observing in her mirror. Isolated in her tower, she is entranced by the vibrant life of Camelot shown to her only as shadows cast upon her mirror. Despite knowing that a mysterious curse is tied to her looking directly upon Camelot, she cannot resist the pull of the outside world. This comes to a climax when she sees Sir Lancelot through her mirror, described as 'bold' and shining, and the temptation overwhelms her. She abandons her loom and looks out the window, which immediately brings upon her the fulfillment of the curse.
Looking out the window signifies her choice to embrace the fullness and risk of the living world over the safety of her secluded, shadow-filled existence. It represents a moment of human defiance against an arbitrary fate, a critical point where she asserts her free will to engage with life, even if it leads to her destruction. This pivotal decision underscores themes of freedom, fear, isolation, and the human yearning for connection and participation in the wider world.